Process for the production of tanned pictures



Patented Nov. 23,1937

UNITED STATES PATENT. OFFICE PROCESS FOR THE PRODUCTION OF TANNED PICTURES No Drawing. Application November 29, 1932, Serial No. 644,920. In Germany December 9, 1931 4 Claims.

The present invention relates to light-sensitive material, particularly for the preparation of pietures to be produced by tanning action.

One object of my invention are light-sensitive colloid layers which are adapted to yield after exposure to light, so-called tanned pictures. These light-sensitive layers are obtained by incorporating in an organic colloidal material a light-sensitive diazo compound of high molecular 1 weight the light-decomposition products of which are capable of directly tanning the colloidal material. The colloidal material thus sensitized is then brought upon a suitable support there forming the sensitive layer, or'it is used as such to 15 form an independent layer or film. The use of the said diazo compounds of high molecular weight involves the advantage that the colloids are already tanned during the exposure, without it being necessary, as in. the known processes, to 20 subsequently treat the exposed layers with a chrom'ate or the like. It is thus possibleto avoid the use particularly of the poisonous chromates which frequently produce disagreeable eczema, which is, 01 course, prejudicial to their utiliza- 25 tion in practice. I

Light-sensitive diazo compounds whose lightdecomposition products are capable of tanning colloids are generally those possessing a fairly large molecule, for instance: the diazo com- 30 pounds of 4-amino-1(N-methyl-S-naphthalenetetrahydride-1.2.3.4) -aminobenzene having the formula:

BOIH S0311 4"-amino-2"-carboxy-1" N-phenyl-4.4'-diami- 50 no-1.1'-diphenyl-methane having the formula:

56 and furthermore the products obtainable by. the

condensation of aldehydes with diazo compounds, for instance of formalin with 4'-diazo-1.1'-diphenylamine.

These latter condensation products are described and claimed in the co-pending application Serial No. 672,346 of M. P. Schmidt and myself, filed May 22, 1933. The diazo compounds suitable for the present invention contain at least three six-membered carbocyclic rings and are constituted according to the following general formula:

of cellulose esters, water-insoluble cellulose ethers or regenerated cellulose.

The preparation of the light-sensitive colloid layers can be adapted in the usual manner to the particular purpose to which they are to be applied. For pigment printing, for instance, a feebly acidified solution of one of the above diazo compounds is added to a colloidal substance colored with a finely divided inorganic or organic pigment, the emulsion is cast on paper and dried. In order to obtain a paper suitable for producing gum printing eifects, a solution of methyl cellulose is colored with a pigment, sensitized as above described and applied in a thin layer on paper. The exposed material is developed by treatment with a solvent for the colloid. If, for instance, gelatine is employed as colloidal substance, the colloid at the places not struck by light may be dissolved with the aid of warm water.

It is a particular advantage of the present invention that it permits one to obtain layers type printing, such as addition of acids and/or 1 stabilizers, may be utilized with advantage.

The process of this invention is intended to be used in those cases where hitherto chromates were used for the preparation of pictures to be produced. by tanning action.

light-sensitive substances. toco'lioid "layers in I order "to thus harden or tan the latter by the exposure without the use of a chromate. This proposed process failed, however, in practice, since the said dyestufis have but a small sensitivity to light and since the layers produced therewith had to be exposed to light in a moist state. The present invention avoids all of these drawbacks.

The following examples illustrate the invention:

1.--An emulsion is prepared from 10 grams of gelatine, 1.5 grams of iron oxide red, 0.8 gram of the zinc chloride double salt of the diazo compound of 4-amino-1(N-methyl-B-naphthalenetetrahydride-1.2.3.4) -aminobenzene, 2 grams of acetic acid of 50 per cent strength and 80 grams of water. It is applied on paper. After drying, a pigment paper is obtained which, after exposure to light, is transferred in the usual manner with the aid of cold water on another support where it can be developed with water of about 40 C.

2.-For the 0.8 gram of the diazo compound named in Example 1, there is substituted 1 gram of the diazo compound of 4"-amino-2"-carboxy-,1" N-phenyl-4-amino-4'-hydroxy-1.1 diphenylmethane having the formula:

COOH

and 2 grams of sodium 1.3.6-naphthalenetrisulfonate are furthermoreadded. The papers prepared with the emulsion so obtained are worked up in the usual manner.

3.40 grams of a 2 per cent. aqueous solution of water-soluble methylcellulose are finely triturated with 1 gram of soot; a solution of 0.5 gram of a diazo compound, obtainable by condensing para-formaldehyde with the sulfate of 4-diazo-1.1'-diphenylamine, and 0.7 gram 'of citric acid in 50 grams of water is then added. The mixture thus obtained is applied on to paper and dried. The finished paper is exposed to light under a pattern; a negative picture of the pattern may be developed with the aid of cold water. 4.-5 grams of animal glue, 0.6 gram of the diazo compound referred to in the preceding example and 0.7 gram of citric acid are made into an emulsion with 100 grams of Water. The emulsion is filtered, applied in the form of a thin layer on a copper plate and dried. The plate is exposed to light under a pattern, colored Proposals have" been -made.'(cf. Eder Aus- .'fiihrliches zHandbuch .derPhotographie, VOL-w .ume IV; Znd-part, 4th edition, page. 39) to addvdyestuffs, suchas auramine and erythrosine, as

with the aid r methyl violetand washed. it

is. aiteretreated} in }'a .suitable manner and the negative picture produced can then be etched "into the copper.

It is to be understood that in the followin claims the term diazo compound" comprises tetrazo compounds also and, furthermore, the said compounds not only as such but also their salts or double salts with acids, salts or the like.

I claim:

1. Process for the production of tanned pictures which comprises exposing under a pattern a light-sensitive layer comprising a colloidal substance capable of being tanned and a lightsensitive aromatic diazo compound of high molecular weight, which contains at least three sixmembered carbocyclic rings and is constituted according to the formula R X-R1, wherein X stands for a member of the group consisting of CH2, oxygen and an imino group and R and R1 for a radical of the group consisting of aromatic and hydroaromatic radicals of the benzene and naphthalene series atleast one of which contains a diazo group, and then dissolving the colloid at the unexposed parts.

2. Process for the production of tanned pictures which comprises exposing under a pattern a light-sensitive layer comprising a colloidal substance capable of being tanned and a lightsensitive condensation product obtained by condensing 4'-diazo-1.1'-diphenylamine with. paraformaldehyde and then dissolving the colloid at the unexposed parts.

3. Process for the production of tanned pictures which comprises exposing under a pattern a light-sensitive layer comprising a colloidal sub stance capable of being tanned and the diazo compound of 4 -amino-2 -carboxy-1 -N-pheny1-4-amino-4'-hydroxy 1.1 diphenyl-methane and then dissolving the colloid at the unexposed parts.

4. Process for the production of tanned pictures which comprises exposing under a pattern a light-sensitive layer comprising a gelatinous substance capable of being tanned and a light-sensitive aromatic diazo compound of high RUDOLF ZAHN. 

